The new rotation system for the ECB's Governing Council means Jens Weidmann, the governor of the German Bundesbank, will sit out the council meetings in May and October next year. Weidmann has traditionally been critical of ECB aggressive stimulus measures, so his prospective absence increased market speculation the ECB might yet launch a QE program as early as May.

The U.K.'s FTSE 100 continued to marginally underperform other bourses on Thursday, as Scots headed to the polls for the country's independence referendum. The index closed provisionally 0.5 percent higher.

The vote is seen as close, but bookmakers are predicting a win for the "No" campaign.

The Italian FTSE MIB pared gains to close unofficially 0.1 percent up, after the International Monetary Fund cuts it growth outlook. Its economy is seen shrinking in 2014 for a third-year running.

Bayer shares surge

In stocks news, Bayer rose to the top of benchmarks. The German firm said on Thursday that it was planning to float its plastics unit as a separate company, which led its shares to closed around 6.2 percent higher.

Food wholesaler Booker Group ended roughly 7.8 percent higher after the London-listed company announced a rise in second-quarter sales.

Merger talk in the industrials sector led Sulzer shares to close around 8.9 percent up. The Swiss company confirmed it was in discussions with Dresser-Rand regarding a potential deal.